WebSockets: Full-Duplex Real-Time Streams

HTTP is request-driven; a client must request data before the server responds. WebSockets break this constraint by upgrading an existing HTTP connection into a stateful, bidirectional TCP stream.

The client initiates this by sending an HTTP request containing the header "Upgrade: websocket". If accepted, the server returns status 101, and the TCP socket remains open for low-overhead message frames.

Once upgraded, either the client or the server can push raw text or binary data frames at any time without repeating cookies, user-agents, or headers. WebSockets are optimal for chats, financial tickers, and live telemetry panels.